Post Growth Fabrication of GaAs/AlGaAs Reflection Modulators via Impurity Free Disordering

Abstract

Disordering of GaAs/AlGaAs multiple quantum well asymmetric Fabry-Perot modulators (AFPM) was carried out using impurity free vacancy diffusion (IFVD), involving the deposition of a SiO 2 cap followed by rapid thermal annealing at 930°C. Blue shifts of up to 52 meV, while maintaining clearly resolved heavy and light hole excitons, were achieved. This enabled the production of both normally-off (contrast >10 dB for -5 V bias) and normally-on (reflection change >30% for -8V) AFPM's from the same wafer, thus displaying how IFVD can be used to tailor the optoelectronic properties after growth.